1. Technical Field
This invention relates to components of internal combustion engines and, more particularly, to an all ceramic cylinder head or a fiber reinforced ceramic matrix composite liner for internal combustion engine comprising a cylinder head made of structural fiber reinforced ceramic matrix composite.
2. Background Art
A typical internal combustion engine comprises an engine block containing one or more cylinders in which pistons move up and down as the result of the burning of fuel therein. The cylinders are covered and closed by a cylinder head 10 as shown in FIGS. 1 and 2. The burning of the fuel under compression releases energy as motion and heat. Accordingly, the parts of the engine tend to get very hot. To prevent metal damage from over-heating and problems of lubrication break-down and possible engine seizure from excessive thermal expansion of parts, the heat must be conducted away so as to limit the operating temperature of the engine to design standards. This is normally done in one of two ways. As shown in FIG. 1, the cylinder head 10 can have a water jacket 12 built into it wherein the water jacket 12 is connected via the connecting tubes 30, 32 to the water circulated through the block and an air-cooled radiator. As shown in FIG. 2, the cylinder head 10 can incorporate fins 14 which provide a large surface area to radiate heat directly to air passing therethrough. Motorcycles, lawnmowers, and the like, tend to use the fins 14 while automobile and truck engines favor a water jacket 12 due to the high heat loads generated in their operating environment in conjunction with allowable under-hood temperature requirements. In addition, the water jacket 12 provides a heat source for the vehicle's heating, ventilation and air conditioner (HVAC) system.
In a co-pending application entitled HIGH-EFFICIENCY, LOW POLLUTION ENGINE by the inventors herein, Ser. No. 08/515,604, filed on Aug. 16, 1995 and assigned to the common assignee of this application, an improved structural fiber reinforced ceramic matrix composite (FRCMC) material is disclosed having high breakage resistance and particular applicability to use for parts in a high temperature internal combustion engine the teachings of which are incorporated herein by reference. A novel engine design employing parts made of that FRCMC material is also disclosed. The engine runs at very high temperatures so as to improve fuel efficiency and reduce the emission of unburned pollutants. While one could employ a ceramic-lined metal cylinder head with that engine according to techniques disclosed in the co-pending application entitled METHODS AND APPARATUS FOR MAKING CERAMIC MATRIX COMPOSITE LINED AUTOMOTIVE PARTS AND FIBER REINFORCED CERAMIC MATRIX COMPOSITE AUTOMOTIVE PARTS by the inventors herein, Ser. No. 08/515,849, filed on Aug. 16, 1995 and assigned to the common assignee of this application, it would be preferable to have the entire cylinder head made of the FRCMC material or a liner formed from the FRCMC material. While the ceramic engine is not as prone to thermal damage as a metal engine, an un-cooled ceramic cylinder head being at the top of the engine block and directly under the hood of the automobile would most likely achieve unacceptable "touch" temperatures, which would lead to unreasonable engine compartment temperatures and possible even destroy the paint on the hood. Thus, for entirely different reasons, the reduction of heat at least at the outer surface of a ceramic cylinder head remains a problem to be dealt with. Moreover, automobiles and trucks still favor a hot water passenger compartment heating system over the alternatives such as hot air or burned fuel heaters.
Wherefore, it is an object of the present invention to provide a ceramic cylinder head or headliner fabricated of a structural fiber reinforced ceramic matrix composite material for an internal combustion engine which includes provision for reducing its temperature level at the outer surface thereof.
It is another object of the present invention to provide a ceramic cylinder head or headliner fabricated of a structural fiber reinforced ceramic matrix composite material for an automobile which can be positioned under an automobile hood without damaging other vehicle systems from radiated heat.
It is still another object of the present invention to provide a ceramic cylinder head or headliner fabricated of a structural fiber reinforced ceramic matrix composite material for an automobile which provides or allows for hot water for a passenger compartment heating system.
Other objects and benefits of this invention will become apparent from the description which follows hereinafter when read in conjunction with the drawing figures which accompany it.